The invention relates to an elastic link bearing for wheel suspensions of motor vehicles, especially for the body linkage of a transverse link, and, more particularly, to an elastic link bearing formed from two mutually corresponding bearing elements.
The bearing elements are placed coaxially opposite one another and each has a receiving sleeve which can be slipped onto and braced axially on a common axle fixed to the body. The receiving sleeve carries in the outer end region an end collar pointing radially outwards, an intermediate sleeve rotatable on the receiving sleeve and supported on the end collar of the latter, and an elastomeric bush which is vulcanized onto the intermediate sleeve. By means of a vulcanized-on connecting bush having a supporting flange at the outer end, the elastomeric bush can be pressed with a bonding effect into the link lug up to the abutting of the supporting flange and has an outer collar vulcanized onto the end face of the supporting flange facing away from the link lug. After the two bearing elements have been pressed into the link lug their receiving sleeves bear against one another with their inner end faces.
A link bearing of this type is known from GB-2,202,923 A, FIG. 2. In this construction, the elastomeric bushes are pressed into the link lug. Their installation position is at the same time determined by the annular disc which is vulcanized onto the outer collar engaging over the link lug and belonging to the elastomeric bushes and, during the pressing-in operation, depending on the radial overlap, comes to bear against the respective end face of the link lug only unreliably of elastic shearing stresses.
When the two bearing elements are in the installation position, although their receiving sleeves are supported on one another with their end faces located within the link lug, nevertheless a relatively large spacing remains between the end faces of the two intermediate sleeves located within the link lug. The result of this is that, when axial forces act on the link lug, such as occur, for example, during braking operations, only the bearing element located at the front in the braking direction is deformed elastically in the axial direction, i.e. subjected to shearing and compressive stresses.
The result of the axial spacing present between the intermediate sleeves of the two bearing elements is that, under the effect of axial force, the element at the rear in the direction of travel, because of the radial tension existing between its elastomeric bush and the link lug, is displaced relative to its receiving sleeve in the direction of the effective axial force and the intermediate sleeve is thereby moved away from the end collar of the receiving sleeve.
The entire axial force thus has to be supported by the front bearing element alone, and therefore this runs a high risk of wear and corrosion. The intermediate sleeves of the two bearing elements are each arranged on the sliding bush which is attached rotatably and displaceably to the receiving sleeve and which engages with an outer collar between the end collar of the receiving sleeve and the adjacent end face of the intermediate sleeve. The mutually rotatable faces of the sliding bush and receiving sleeve are lubricated.
Under the effect of axial force, the sliding bush of the rear bearing element is taken up via the intermediate sleeve attached firmly to it, its outer collar being lifted off from the end collar of the receiving sleeve. When the link bearing is relieved of axial force, the link lug together with the rear bearing element is returned abruptly into the constructional position again due to the restoring force occurring as a result of the shearing stress of the elastomeric bush of the front bearing element. The outer collar of the sliding bush at the same time strikes against the end collar of the receiving sleeve. The knocking noise thus occurring is noticed in the vehicle interior and is detrimental to motoring comfort. Moreover, lubricating grease present between the sliding faces of the two collars is displaced during the impact, thus impairing the lifetime of the rear bearing element. Finally, under the influence of axial force, the link support base within the link bearing becomes shorter, thereby resulting in inclinations of the link when the radial and cardanic link loads are superposed. Under radial link loads in particular, the elastomeric bushes are damaged in the region of the inner circumference of the annual disc vulcanized onto these by its sharp end edges limiting the central disc bore on account of their knife-like behavior.
In addition to the known bearing construction of GB 2,202,923.A, German Patent Document 2,623,870 already makes known an elastic link bearing, of which the two mutually corresponding bearing elements each have an elastomeric bush which is vulcanized onto an intermediate sleeve and which is supported by means of a vulcanized-on annular disc on the respective end face of the link lug to be mounted.
The intermediate sleeves are supported on one another and are arranged on a common receiving sleeve, by means of which they are braced axially relative to one another and which is itself held on a bearing axle.
Apart from the fact that the intermediate sleeves are braced between bracket legs and consequently this link bearing constitutes a torsion bearing, under the effect of axial force on the link lug the latter is lifted off from the annular disc of the bearing element located at the rear, as seen in the direction of force, and strikes audibly against this as soon as the link lug is relieved again in the axial direction.
Machine-Design/Aug. 10, 1989, page 44, discloses a link bearing, in which the connection between the elastomeric bushes, which are each vulcanized onto an intermediate sleeve, of its two bearing elements and the link lug is already made by means of a respective connecting bush vulcanized onto this and being pressable with a bonding effect into one end face of the link lug and equipped with an outer flange vulcanized onto an outer collar of the respective elastomeric bush.
In this bearing construction, however, the intermediate sleeves are mounted on the receiving sleeve so as to be mutually displaceable in the axial direction, so that, under the effect of axial force, the intermediate sleeve together with the elastomeric bush of one bearing element can shift axially.
There is therefore needed an improved elastic link bearing in a design of the type mentioned above with respect to GB 2,202,923A operating in such a way that adverse influences on motoring comfort, service life and functioning are avoided.
This need is met according to the present invention, by an elastic link bearing formed from two mutually corresponding bearing elements. The bearing elements are placed coaxially opposite one another and each has a receiving sleeve which can be slipped onto and braced axially on a common axle fixed to the body. The receiving sleeve carries in the outer end region an end collar pointing radially outwards, an intermediate sleeve rotatable on the receiving sleeve and supported on the end collar of the latter, and an elastomeric bush which is vulcanized onto the intermediate sleeve. By means of a vulcanized-on connecting bush having a supporting flange at the outer end, the elastomeric bush can be pressed with a bonding effect into the link lug up to the abutting of the supporting flange and has an outer collar vulcanized onto the end face of the supporting flange facing away from the link lug. After the two bearing elements have been pressed into the link lug their receiving sleeves bear against one another with their inner end faces. When an axial load occurs, the intermediate sleeves bear against one another with force transmission.
Thus, in the link bearing according to the present invention, under the influence of axial force it is possible, where appropriate, for there to be only a minimal axial displacement of the intermediate sleeve of one bearing element in relation to the receiving sleeves. This prevents the possibility that, under the effect of axial force, one of the intermediate sleeves will move away from the end collar of the receiving sleeve carrying it, to such an extent that knocking noises occur, and that lubricating grease between the mutually engaged sliding faces of the end collar and intermediate sleeve will be displaced when the bearing is relieved of axial force.
Equipping the elastomeric bush of the bearing elements with a connecting bush vulcanized onto this and pressable with a bonding effect into one of the end faces of the link lug ensures an interconnection of elastomeric bushes and link lug which guarantees that, under the influence of axial force, the two elastomeric bushes are subjected to a uniform stress. This affords the advantage that a substantial relief of the elastomeric bush and of the mutually engaged sliding faces of the bearing element located to the front in the direction of force is achieved.
Finally, the axial dimensioning of the two intermediate sleeves on the receiving sleeves and the slip-free connection of the elastomeric bushes and link lug make it possible to reduce the constructional length of the elastomeric bushes, without functional disadvantages arising from this, especially a shortening of the link support base.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.